With the progress of the digital technology, an application range of a digital device is being expanded continuously, and a software system adapted to the digital device is being diversified continuously. However, digital devices currently used for demonstrating or simulating a system all utilize a computer and related software to carry out the whole process without any contact to an external real object. For example, when a demonstration is performed to a user by using a multimedia software in a computer, all processes are performed in a virtual environment created by the multimedia software, thus it is impossible to interact with the real object.